KR100690003B1 - Material of Pixel Electrode in Liquid Crystal Display and Method of Etching the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pixel electrode material suitable for preventing corrosion or damage to metal wiring during pixel electrode patterning and an etching method thereof.

The pixel electrode material of the liquid crystal display device according to the present invention is characterized by being made of a transparent conductive material having an amorphous structure which is etched with an etchant of weak acid including oxalic calculation.

Description

Pixel electrode material and liquid crystal etching method of liquid crystal display device {Material of Pixel Electrode in Liquid Crystal Display and Method of Etching the same}             

1 is a cross-sectional view of a lower transparent substrate showing a state in which a pixel electrode is patterned in a conventional four mask process technology.

2A through 2D are cross-sectional views of lower transparent substrates showing stepwise methods of patterning lower transparent substrates of liquid crystal display devices according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1,31: transparent substrate 2a, 32a: gate electrode

2b and 32b: Gate lines 2c and 32c: Gate pad

3,33 gate insulating film 4,34 active layer

5,35 ohmic contact layer 6a, 36a source electrode

6b, 36b: drain electrode 7, 37: passivation layer

8,9,38,39: contact hole 10a, 40a: pixel electrode

10b, 40b: Protective electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly, to a pixel electrode material suitable for preventing corrosion or damage to metal wiring during pixel electrode patterning and an etching method thereof.

The liquid crystal display of an active matrix driving method displays a natural moving image using a thin film transistor (hereinafter referred to as TFT) as a switching element. Such liquid crystal display devices can be miniaturized compared to CRTs, and are widely used in personal computers and notebook computers, as well as office automation devices such as photocopiers, portable devices such as cell phones and pagers. .

The manufacturing process of such a liquid crystal display device is divided into substrate cleaning, substrate patterning, alignment film formation, substrate bonding / liquid crystal injection, and mounting process. In the substrate cleaning process, foreign substances on the substrates before and after the upper and lower substrates are patterned are removed using a cleaning agent. In the substrate patterning process, the upper substrate is patterned and the lower substrate is patterned. A color filter, a common electrode, a black matrix, and the like are formed on the upper substrate. Signal lines such as data lines and gate lines are formed on the lower substrate, and TFTs are formed at intersections of the data lines and gate lines, and pixel electrodes are formed in the pixel region between the data lines and the gate lines so as to be connected to the source electrodes of the TFTs. Is formed. In the substrate bonding / liquid crystal injection process, an alignment film is coated on the lower substrate and rubbed, followed by an upper / lower substrate bonding process using a seal material, liquid crystal injection, and an injection hole encapsulation process. In the mounting process, a tape carrier package (TCP) in which integrated circuits such as a gate drive integrated circuit and a data drive integrated circuit are mounted is connected to a pad portion on a substrate.

In the patterning process of the lower substrate, a plurality of masks are required to pattern the electrodes of the TFT, the active layer and the ohmic contact layer, the contact hole of the insulating layer, and the pixel electrode. Since the number of masks is directly related to the number of processes and production cost, researches to reduce the number of masks are actively conducted in each manufacturer and research institute. As a result, a method of patterning a lower substrate using four masks has been proposed. In practice, the lower substrate is patterned using four masks, a mask for patterning a gate metal layer, a mask for patterning an ohmic contact layer and a source / drain metal layer simultaneously, a passivation layer, a semiconductor layer, and a gate insulating film simultaneously. A mask for patterning and a mask for patterning the pixel electrode are required.

Referring to FIG. 1, the transparent conductive layer deposited on the transparent substrate 31 is wet-etched so that the gate line 32b is exposed during the patterning of the lower transparent substrate using the conventional four masks. do. The etching of the transparent conductive layer leaves the protective electrode 40b connected to the gate pad 32c through the pixel electrode 40a and the contact hole 39 in the transparent substrate 31. In the array region, the gate electrode 32a, the gate insulating film 33, the active layer 34, the ohmic contact layer 35, the source / drain electrodes 36a and 36b and the passivation layer 37 are formed in the TFT and the pixel region. Are stacked. The pixel electrode 40a is connected to the drain electrode 36b through the contact hole 38. Since the transparent conductive layer on the gate line 32b is removed during the patterning of the pixel electrode, the gate line 32b is exposed to the atmosphere. In the pad region, the gate insulating layer 33, the active layer 34, and the passivation layer 37 are stacked to cover the gate pad 32c, and the protective electrode 40b is formed on the gate pad 32c through the contact hole 39. Connected.

The conventional patterning process of the lower transparent substrate using four masks has a problem that the gate metal layer is corroded or damaged during the patterning of the pixel electrode. In detail, as the material of the transparent conductive layer, indium tin oxide (hereinafter referred to as "ITO") of a polycrystalline structure is generally used and mixed in a composition ratio as shown in Chemical Formula 1 below.

ITO = InO ₃ (90%) + SnO ₂ (10%)

ITO is deep etched and wet etched into an etchant of a strong acid such as HCl. An etchant of such a strong acid is reacted with indium (In) and tin (Sn) to remove ITO as shown in Chemical Formulas 2 to 4 below.

InO ₃ + 6HCl → 2InCl ₃ + 3H ₂ O

SnO ₂ + 4HCl → SnCl ₄ + 2H ₂ O

In _x Sn _y O _z + nHCl → AInCl ₃ + BSnCl ₄

However, when the gate metal layer is made of aluminum (Al) or an aluminum compound, the gate metal layer, that is, the gate line 32b exposed during the pixel electrode patterning, is corroded by reacting with the ITO etchant.

Accordingly, it is an object of the present invention to provide a pixel electrode material of a liquid crystal display device and an etching method thereof, which are suitable for preventing corrosion or damage of metal wiring during pixel electrode patterning.

In order to achieve the above object, the pixel electrode material of the liquid crystal display device according to the present invention is characterized by consisting of a transparent conductive material of an amorphous structure which is etched with an etchant of weak acid including oxalic calculation.
The amorphous transparent conductive material may be any one of indium zinc oxide, indium tin zinc oxide, and amorphous indium tin oxide.
The etchant is characterized in that it comprises (COOH) ₂ .

The pixel electrode material etching method of the liquid crystal display device according to the present invention comprises the steps of forming an amorphous transparent conductive material on the gate metal layer, and etching the transparent conductive material layer of the amorphous structure with an etchant of a weak acid including an oxalic calculation Forming a pixel electrode pattern.
The transparent conductive material is characterized in that any one of indium zinc oxide (Indium Zinc Oxide), indium tin zinc oxide (Indium Tin Zinc Oxide), amorphous Indium Tin Oxide (Amorpous Indium Tin Oxide).
The etchant is characterized in that it comprises (COOH) ₂ .
Other objects and features of the present invention in addition to the above objects will become apparent from the following description of the embodiments with reference to the accompanying drawings.

delete

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2A, aluminum (Al) may be sputtered on a transparent substrate 1 including an array region in which TFTs and pixel electrodes are formed and a pad region in which pads connected to gates / drains are formed. Alternatively, a gate metal material such as an aluminum compound is deposited to form a metal thin film. The metal thin film is patterned by a photolithography process. When the metal thin film is patterned, the gate electrode 2a and the gate line 2b remain in the array region of the transparent substrate 1, and the gate pad 2c remains in the pad region.

Referring to FIG. 2B, a gate insulating film 3 is entirely deposited on the transparent substrate 1 to cover the gate electrode 2a, the gate line 2b, and the gate pad 2c, and the active layer 4 and The ohmic contact layer 5 is laminated. The gate insulating film 3 is made of an inorganic insulating material or an organic insulating material such as silicon oxide (SiO _x ) or silicon nitride (SiN _X ), and the active layer 4 is made of amorphous silicon or polycrystalline silicon which is not doped with impurities. The ohmic contact layer 5 is formed of amorphous silicon or polycrystalline silicon doped with N-type or P-type impurities at a high concentration.

Referring to FIG. 2C, a metal alloy such as molybdenum (Mo), titanium or tantalum, or a metal alloy such as molybdenum alloy (Mo alloy) such as MoW, MoTa, or MoNb as the source / drain metal may cover the ohmic contact layer 5. It is deposited on the transparent substrate 1 by a chemical vapor deposition (CVD) method or a sputtering method. The source / drain metal layer thus deposited makes ohmic contact with the ohmic contact layer 5. The source / drain metal layer and the ohmic contact layer 5 are simultaneously patterned by a photolithography method. The source electrode 6a and the drain electrode 6b and a data line (not shown) are formed in the array region, and a data pad connected to the data line is formed in the pad region.

Referring to FIG. 2D, a passivation layer material includes an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material having a low dielectric constant such as acrylic organic compound, BCB (benzocyclobutene), or PFCB (perfluorocyclobutane) as a transparent substrate. It forms on (1). The passivation layer 7, the active layer 4 and the gate insulating film 3 are simultaneously patterned by the photolithography method and remain only in the TFT, the pixel region and the pad region. At this time, the gate line 2b is exposed. At the same time, the passivation layer 7 has a contact hole 8 for exposing the drain electrode 6b, a contact hole 9 for exposing the gate pad 2c, and a contact hole for exposing the data pad (not shown). Not formed). After the passivation layer 7, the active layer 4, and the gate insulating film 3 are simultaneously patterned, indium zinc oxide (IZO), indium zinc oxide (IZO), which is a transparent conductive material having an amorphous structure, is used as the pixel electrode material. Indium Tin Zinc Oxide (ITZO) and Amorphous Indium Tin Oxide (a-ITO) are deposited on the transparent substrate 1. Here, amorphous indium tin oxide (a-ITO) may have an amorphous structure by injecting H ₂ O into the chamber during sputtering of indium tin oxide (ITO). Subsequently, the pixel electrode 10a and the protective electrode 10b are patterned by placing a mask on the pixel electrode layer deposited on the entire surface, undergoing an exposure and development process, and then wet etching. The patterned pixel electrode 10a is connected to the drain electrode 6b through the contact hole 8, and the protective electrode 10b is connected to the gate pad 2c and the data pad (not shown) through the contact hole 9. do. Here, since the pixel electrode layer is a transparent conductive material of amorphous structure, it is easily and quickly etched even in weak acid. An oxalic acid such as (COOH) ₂ may be used as the etchant.

As described above, the pixel electrode material of the liquid crystal display device and the etching method thereof according to the present invention select the transparent conductive material having an amorphous structure which is easily etched even in weak acid as the pixel electrode material as the pixel electrode material. As a result, the pixel electrode material of the liquid crystal display device and the etching method thereof according to the present invention are strong acids for removing the pixel electrode material in a state in which the gate metal layer and the pixel electrode are in direct contact with each other by etching the pixel electrode material with weak acid. The etchant of can prevent the gate metal layer from corroding or damaging.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (8)

A liquid crystal display device in which a pixel electrode pattern is formed by etching a pixel electrode material on a gate metal layer, And the pixel electrode is made of a transparent conductive material having an amorphous structure which is etched with an etchant of weak acid including oxalic calculation. The method of claim 1, The amorphous transparent conductive material may be any one of indium zinc oxide, indium tin zinc oxide, and amorphous indium tin oxide. Pixel electrode material. delete The method of claim 2, The etchant comprises (COOH) _2. The pixel electrode material of the liquid crystal display device. In the method for manufacturing a liquid crystal display device in which a pixel electrode pattern is formed by etching the pixel electrode material of the gate metal layer, Forming a transparent conductive material of amorphous structure on the gate metal layer; And etching the transparent conductive material layer of the amorphous structure with an etchant of a weak acid including an oxalic calculation to form a pixel electrode pattern. The method of claim 5, wherein The transparent conductive material may be any one of indium zinc oxide, indium tin zinc oxide, and amorphous indium tin oxide. Etching method. delete The method of claim 6, And the etchant comprises (COOH) ₂ .

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